Я работаю над приложением с фрагментами (приложение с только активностью, но с несколькими фрагментами).
Проблема, с которой я столкнулся, заключается в том, что когда я перехожу к фрагменту и возвращаюсь (кнопка возврата системы) к исходному фрагменту, его RecycleView теперь пуст.
Странная вещь в этом состоит в том, что когда я перехожу к одному и тому же фрагменту из другого фрагмента (также с RecycleView), проблема не возникает.
Ниже я разместил два фрагмента с помощью RecycleView и MainActivity.
Кто-нибудь знает, почему это происходит?
Фрагмент, который имеет , имеет проблему:
public class FavEventFragment extends Fragment implements RecyclerView.OnItemTouchListener {
private static final String PAGE_NAME = "Saved Events";
private TextView noEventsTextView;
FavEventAdapter adapter;
RecyclerView recyclerView;
private EventViewModel eventViewModel;
private List<Event> favEvents;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_favevent, container, false);
MainActivity.changeLayoutWeight(true);
MainActivity.setPageName(PAGE_NAME);
favEvents = new ArrayList<>();
recyclerView = rootView.findViewById(R.id.favEvent_list);
noEventsTextView = rootView.findViewById(R.id.noFavEventsText);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
eventViewModel = ViewModelProviders.of(this).get(EventViewModel.class);
eventViewModel.getFavEvents().observe(this, new Observer<List<Event>>() {
@Override
public void onChanged(@Nullable List<Event> games) {
favEvents = games;
updateUI();
}
});
setRecycleViewGestures();
return rootView;
}
private void updateUI() {
if (adapter == null) {
adapter = new FavEventAdapter(favEvents);
recyclerView.setAdapter(adapter);
} else {
adapter.swapList(favEvents);
}
}
void setRecycleViewGestures() {
recyclerView.addOnItemTouchListener(new RecycleGestures(getActivity(), recyclerView, new RecycleGestures.ClickListener() {
@Override
public void onClick(View view, int position) {
EventDetailsFragment fragment = new EventDetailsFragment();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.setCustomAnimations(R.anim.enter_from_top, R.anim.exit_to_top, R.anim.enter_from_top, R.anim.exit_to_top);
fragment.setObject(favEvents.get(position));
transaction.addToBackStack(null);
transaction.replace(R.id.fragment_container, fragment, "FRAGMENT").commit();
}
@Override
public void onLongClick(View view, int position) { }
}));
ItemTouchHelper.SimpleCallback simpleItemTouchCallback =
new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
@Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
return false;
}
@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int swipeDir) {
int position = (viewHolder.getAdapterPosition());
eventViewModel.delete(favEvents.get(position));
favEvents.remove(position);
adapter.notifyItemRemoved(position);
}
};
ItemTouchHelper itemTouchHelper = new ItemTouchHelper(simpleItemTouchCallback);
itemTouchHelper.attachToRecyclerView(recyclerView);
recyclerView.addOnItemTouchListener(this);
}
@Override
public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) { return false; }
@Override
public void onTouchEvent(RecyclerView rv, MotionEvent e) { }
@Override
public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) { }
}```
The fragment that **doesn't** have the problem:
public class EventsFragment extends Fragment {
private static final String PAGE_NAME = "Upcoming Events";
private RecyclerView eventList;
private EventAdapter adapter;
private AirsoftRepository airsoftRepository;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_shop, container, false);
MainActivity.changeLayoutWeight(true);
MainActivity.setPageName(PAGE_NAME);
airsoftRepository = AirsoftRepository.getInstance();
eventList = rootView.findViewById(R.id.item_list);
eventList.setLayoutManager(new LinearLayoutManager(getActivity()));
getEvents();
return rootView;
}
private void getEvents() {
airsoftRepository.getEvents(new OnGetEventsCallback() {
@Override
public void onSuccess(List<Event> events) {
adapter = new EventAdapter(events, onClickCallback);
eventList.setAdapter(adapter);
}
@Override
public void onError() {
Toast.makeText(getActivity(), "Please check your internet connection.", Toast.LENGTH_SHORT).show();
}
});
}
OnEventsClickCallback onClickCallback = new OnEventsClickCallback() {
@Override
public void onClick(Event event) {
EventDetailsFragment fragment = new EventDetailsFragment();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.setCustomAnimations(R.anim.enter_from_top, R.anim.exit_to_top, R.anim.enter_from_top, R.anim.exit_to_top);
fragment.setObject(event);
transaction.addToBackStack(null);
transaction.replace(R.id.fragment_container, fragment, "FRAGMENT").commit();
}
};
}